We are veering off to the novel here, but in it Vito finds out about some of Fredo's exploits in Vegas, like banging cocktail waitresses two at a time, and as a straight laced old school guy, he is shamed and angered that Fredo would dishonor the family that way. I think there is even some comment that Fredo is aware that his father is "sore" at him.
"Io sono stanco, sono imbigliato, and I wan't everyone here to know, there ain't gonna be no trouble from me..Don Corleone..Cicc' a port!"
"I stood in the courtroom like a fool."
"I am Constanza: Lord of the idiots."
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